I'm trying to use up a stash of 6DJ8s (I know, lucky me). I was thinking of using them for a MM phono stage, but you can't get more than about 34dB of gain from two 6DJ8 sections.

I could put a big honkin' low mu triode on the end to add another 10dB of gain, but that seems wasteful, and the THD would go much higher as well.

What about using up another 6DJ8 section as an anode follower on the output? Yes, the input impedance would be pretty low, but I could put the EQ between the first and second stages, and keep the input impedance of the anode follower output stage up at 47k ohms or higher. The output impedance should be low enough (1k or 2k, something like that).

Why not? What's not to like about it? Negative feedback?
--

New with original packing.
Bought Usher tweeters, but received the wrong model.
These are 4 ohm and I have no use for them.
Maybe I'll post pics later.

$80 shipped conUS

http://www.usheraudio.com.tw/wp-content/download/speaker/9950C-15.pdf

Replaced the IR21844’S on this board rested them after replacement and they both test good .

Does anything else typically fail on these boards ?

When I install the driverboard in the amp it will power up for a split second and then go into protection mode .

I tested all of the regulators all test fine amp is producing both positive and negative rail voltage .

FS: Rival 7'' woofers OEM

Rival OEM 7'' woofers - 1 pair available (New)
R(e) = 7.29 Ohms
f(s) = 33.30 Hz
Q(ms) = 7.166
V(as) = 31.54 liters
M(ms) = 21.09 grams
Q(es) = 0.308
C(ms) = 1.15 mm/N
Sd= 131.000 cm²
Q(ts) = 0.3
L(e) = 0.177 mH at 10kHz
BL = 10.06
SPL = 87.5 dB SPL 1W/1m


Woofers: $66.25 USD each (Retail $159 ea)
Boxes: $3.50 USD
Shipping: 36.25 USD
PayPal $4.00 USD
Total: $176.25 USD

I have what is a common failure for my car, the sealed relays in the door module failing from dirty contacts.

The relays are type JSM1-12V-5. I have attached the datasheet.

I can just buy replacements. As I know little about relays, I was wondering if this was a common form factor? Can hardier replacements be sought? TIA

2.5A DHT heater supplies adjustable between 2.5-7.5V internally limited at 4A. However the dissipation limit of the transistor makes them unsuitable for tubes like the 211/845/GM70



These are some of my DIY DHT heater supplies. They are one of the earlier versions without a "pre-regulator". Therefore they are quite low drop.



The topology is that of a voltage controlled current source, that should be outside of the audio spectrum from 20Hz onwards.



They are handmade to my own design, and tested and adjusted to 5.0VDC. Their dropout is about 1.5V at 1A. And their noise+hum is about 500uV/.5mV RMS measured with a Fluke 175 at 500,000 uV (or .5V RMS) ripple on the input.



Permissible dissipation is around 15W on the heatsinks pictured, those are 2.3K/W types. Something that doesnt even come close to the dissipation required to glow a 1.5A 300B at 7.5VDC input. (approx 4W).



Connections are by means of 6.3mm faston spade connectors, i will include a dozen of those as well.



Pros:

• Big heatsink.
• short circuit proof for short periods of time.
• Good noise performance

cons:

• bulky heat sink that is rather hard to mount because you need to drill your own holes in the heatsink.
• Needs external rectifier plus capacitor board to function.

I also have a pair suitable for both 211 or GM70 tubes, these feature the same heatsink but a more expensive opamp and TO247 fet instead of the TO220 transistor on these.



Asking €50 for a pair, and an extra €20 for two CLC rectifier boards. If you order these i can supply extra boards and parts at cost of my new design. Which features a Linear regulator as pre-regulator for lower noise.


Payment: paypal is preferred, shipment through DHL, please inquire about shipping rates beforehand if your outside of the EU.

Got problems with this rectifier and regulator unit. It puts out some 100hz ripple that causes hum in the preamp. It uses an EZ80 as rectifier, 6C19P as power element, EF80 as error amplifier and a 12AU7 as reference. If I remove the 12AU7 reference tube the 100hz ripple is gone and no hum. Of course, the voltage drops to about 200Vdc. I know, some of you will find this circuit a bit strange but this is what the manufacturer has done. But clearly, something is wrong.

I've had these speakers for a very long time, only selling because I'm purchasing a pair of Bastanis Jimi speakers. They are not the greatest looking speakers but they still sound fantastic, and I've heard many systems at vastly higher price points that do not live up to what these can do. My amp is a Decware Zen and the 2W it provides is plenty to power them.

I will throw in a Bottlehead Seduction phono stage (needs tubes), a Red Wine Audio Signature 30, and an Audio-GD DAC 19 Mk3. If anyone would like more pictures just let me know.

$900 for all of that, and I'm in Jacksonville FL. Shipping would be rough on this so picking up would be a far better way to go if the buyer happens to be anywhere nearby.

Thanks
Gary

I'm looking for some help. Having trouble figuring out vent on drawing, I see three compartments on front view, one on side view. I'm confused with front view. Would appreciate some help. Thanks.

*I also posted this on the Apogee Accoustics Forum:

I am looking to change the crossover in my Duetta II's to a Signature crossover.
In researching the parts needed I came across two sites with the crossover schematics.
Unfortunately, the tweeter-mid schematics are different between these 2 sites.
First difference is the inductor at output. One lists it at 6.4mH the other at 4.3mH.
Second difference is in the jumpers for schematics. The jumper for the low position results in the same equivalent circuit but the normal and high positions are different. The components are the same.
Schematic one is located here:
http://www.apogeespeakers.com/projectstech/Duetta_Signature_crossover.pdf
Schematic two is located here:
http://www.integracoustics.com/MUG/MUG/tweaks/apogee/duetta_xo.jpg
So the big question is which one is correct?

Hello Folks,

I'm having a very weird issue with an ADCOM GFA-5800, I have another thread in the Solid State Forum but I'm not getting much of attention, hopefully here Mr Pass or somebody else familiar with his designs will have a clue.

Basically for a long time I thought that the Left Channel was damaged because its at this point going full + 83VDC a the speaker output, so I de-soldered every single component and tested it and re-soldered them back, I even replaced some MOSFETs that I know usually get damaged, based on other GFA-5500s and 5800 that I have fixed, I also changed some resistors that were very close to the 1% tolerance and of course the little electrolytic caps.

It wasn't until I finished all of that yesterday that I thought, OK silly why don't you connect the right channel assembly on the left side of the power supply and vice-versa and see what happens...

Well, I'm glad I did that, it turns out that that other channel had the same behavior and the previously thought damaged channel is perfectly fine in the other side of the power supply with only 12 mV DC offset.

I removed the power supply and again de-soldered every component from that left side and checked them, well only the ones on the regulated +/- 91VDC area, resistors, zener diodes, Transistors, voltage regulators, capacitors... all apparently good.... I have compared voltages with the other side and they all match.

Other observations I have seen are:

1. If I connect both of the Unregulated +/- 81VDC all good, no DC voltage being leaked to speaker outputs nor to the pre-ampfification area.

2. If I connect either of the regulated +/- 91VDC separately everything seems to be fine.

3. If I connect both of the regulated +/- 91VDC that’s when it goes bananas, with or without the +/- 81VDC rails connected...

Any help would be really appreciated.

Thanks,
Alex

These are small pcbs 59x67mm,send me a P.M if yiue are willing to help me...

Hi,


So I'm new to this, and just before I powered everything up I came across a post suggesting that I need to load all the outputs before I power up or I could damage the amplifier.


Having had many commercial amps over the years, this is news to me. I've ordered some 100w 4 Ohm power resistors so I can load the outputs that aren't in use, but these will be dissipating quite a bit of heat.



What's the actual cause of self destruction of unconnected outputs? I saw some comments mentioning that the amp could go into self oscillation and shoot out high voltages killing the output circuitry. Can we not just put a high value resistor or something on the output to load it while not in use, or does it need to match the speaker resistance?

Hi Guys,

Which single chip DAC is good for a project ? No need for I/U conversion, opamps, buffers and such. Power it with a battery and cross fingers good to go.

Thanks.

In my current vehicle I have a satori mw13p-4 in 2.5l which is fine, however due to reflections I found the mw16p-4 to be better due to beaming lower and having less reflected energy from the screen and side window on the opposite side of the vehicle

My question is... considering the drivers are running effectively as midrange playing from 200hz upwards if I was to put the mw16p-4 in a similar sized 2.5l enclosure would this then effect the midrange negatively providing I applied a good amount of poly fill to lower the Q as much as I can?

As far as I know the Q of the enclosure effects it’s bottom end response, as I am crossing it over higher up can I then use an undersized sealed enclosure and not suffer any negative effects?

This question is about the performance of a driver in say a box with a Q of 1.2-1.3 well above fb, the 6” offers me a very big advantage in stage width and I’d like to modify my current enclosures if possible with a different baffle as I just spent a week rebuilding a none reflective dash with a framework and grill cloth as it was having a very negative effect on my stage width on the passenger side

Full range speakers are good at a wide range of frequencies. Often the low end is something that needs augmenting as small full range speakers seem to be very good at mids and highs. Rather than use a FAST design, why not combine complementary full range speakers (largish and smallish) of similar sensitivity and use something like a 1st order crossover which requires the drivers to have good performance 2 octaves beyond the specified crossover point? I feel like full range speakers should cope well with this. If crossed at the right point, wouldn't this be a relatively simple 2 way that overcomes a lot of the limitations of full range speakers?

Are there any validated designs like this?

I realise that I am probably missing something but curious to why this wouldn't be a good idea.

My PC resides approximately 30 feet from my stereo setup. I currently run a 30' USB repeater cable from my PC to my Chord DAC. The 30' cable is not ideal, and there are no good options for upgraded USB cables in that length.

I'm trying to find out if I can use an ethernet cable, convert to USB near the DAC, and use a short USB into the DAC.
OR, if there's another option I could use to achieve using a short USB cable.

My setup is as follows: NAS>ehternet cable>PC>USB cable>DAC>interconnects>amp.

I tried a Bluesound streamer, but wasn't a fan of the sound.

Any advice would be greatly appreciated!

Hi


does anybody have experiences with cheap china-cores like these ones?


Nanocrystalline C Cores, Nanocrystalline C Cores direct from Zhuhai King Magnetics Technology Co., Ltd. in CN


They can't be as bad as they are (comparably) cheap, right?



Thank you!

Tony had a great idea for a SSRP test fixture, so i intend to design this for him and anyone else that needs it for that matter. Perhaps do a group buy.

Octal and Noval double triodes where imagined, i wanted to use PCB material for the top plate, and use M4 standoffs, around the corners. The belton sockets dictate that the standoffs are about 15mm with a washer approximately 1mm thick.

The bottom PCB will contain the sockets and connections for banana jacks.

Heater1 will be connected to the ground plane, and pin 9 of the Noval double triode socket.

I will add another hole in the top plate for a little switch, that will switch pin 5 between H2 and ground, so the fixture is usable with ECC88 and ECC83 (just an example many, many more tubes will fit.


Dimensions are 100x100mm.

Hello all,

I am restoring a set of Quad 2 mono-blocks, and want to move the Quad 22 pre-amp to full digital to analogue (remove all the tubes etc).

Signal pathway will be Tidal Stream --> USB --> DAC --> Volume Control --> Tone Controls --> RCA Phono Out --> Quad 2 mono-blocks.

Any recommendations:

1. Suitable hi-quality DAC that will take USB and unfold MQA with best quality bit rate, minimum 24bit/196Hz
2. Precision rotary volume control suitable for the DAC
3. Preamp and Tone Control Board (Treble, Bass and maybe filters)

Thanks in advance.

Malcolm

I bought these a few years ago, but never found the time to build a DAC, and use them, so putting them up here. Still in original packaging

• 1x FIFO kit
• 1x XO board

$80USD for the lot.

Shipped from Australia

HI,

I'm looking for a power P or N mosfet, I don't need complementary with :

LOW capacitance
HIGH transconductance
70v VDS

Typically a STP16NF06 but with 70v VDS
https://www.st.com/resource/en/datasheet/cd00002501.pdf

or more transconductance than a FQP3N30

thanks

Hi all.
I have a 2 meter ansuz mainz p2 power cable up for sale,like new condition.
New 1650 euros ',want 800 for it🙂

Have anyone tried this circuit, I really like the simplicity of the schematics.
I am wondering if someone here has some experience with the sound qualities of this amp.

Suppose that you make a three way speaker with WS 200 s Visaton woofers times two in about 110 lt enclosure use also Visaton DSM 25 ffl tweeter but also use 2pcs ws 100 for midrange

I was looking at the graph it seems that WS 100 (86db ) if used for midrange and even if times two it will not have any juice in the hi mid area

Do you agree ?

W 100 S - 8 Ohm | Visaton

I am highly terrified to use it with the Li Ion sitting next to my skull.

Gajanan Phadte

I like the Quad ESL57 a lot and I keep reading about LS3/5a being speakers owners of those like. I'd like to swap in Falcon drivers and crossovers so really just looking for something where the drive units are in poor condition/broken. Please send me a PM if you want to discuss it since I'll receive an email notification. Thanks

Edit: I will add that as long as I haven't updated the thread to say I've found a pair, this thread is essentially still open to looking for them, so feel free to send me a message at any time.

Hi all . So I have a Precision Power PC.2350 amp that I recently replaced all of the power mosfets and the output transistors . I get a clean sound wave at both channels with no load connected . At low volumes both channels sound beautiful
When connected to a speaker . But the problem I have is that when I start to raise the volume loud but without clipping the sound wave . I have burned up the same sound card 2 times . These sound card are really not repairable to my knowledge and I don’t have any more to risk blowing up . At this current moment I have replaced the sound card with my last spare one and both channels sound great again . Can Some please help guide me ?

Is there anything I can put in line of a power to class D amp to stop the pop noise on power-up?

Hello all. I would really appreciate some help here being an DIY newbie builder. I have just put together a simple class D amplifier which is powered by a 24V DC power supply. All is good if you turn the amplifier on via its click rotary volume control. However, if you leave it turned up to where you want it and power it off via the mains and back on via the mains power switch it makes a 'not nice' pop to the speakers.

Being a 'electronics know very little' 🙂 Is there anything that I can put in line with the power to the class D board perhaps that will stop this pop happening? A gradual let the power through type of thing perhaps that may prevent it? (links to ebay or whatever would be much appreciated to a newbie builder). I'm assuming its from a surge in and a slower power up would perhaps prevent it doing it.

All I want is to leave it powered on or power on without using the rotary volume as its just going to be adjust and left at a set volume. I'll have a separate preamp to control volume.

I have two JBL mpx1200 amps which are making sometimes very loud pop/noise from speakers when turning off. No inputs connected. Otherwise amplifier works perfectly. There is output/speaker relays but they are possibly too slow when turn-off spike appears.

Here is the power input schematic, would it be good idea to put X2 rated capacitor(s) or series RC snubber or MOV accross primary windings AFTER the power switch? There is just one 0.47uF before switch.

I used Tractrix _V1.4b to design a 185 Hz horn using Inlow sounds .inlowsound.com method of making a mold and building the cones out of paper mache. I am not connected to them in any sense. I have never communicated with him either. Although it probably would have been a good idea. I did just finish and pulled the second horn off the mold. I do not have storage space for the mold and am willing to make someone a terrific deal. It has a 55mm throat and is 610mm in length and 594mm diameter mouth. It is painted with catalyzed urethane automotive paint. Sanded smooth with 2000 grit and polished. I am using Dynaudio D54af for drivers but a low frequency 2" compression driver would be better. I hate to take a hammer to my covid 19 lock down work, but it has to go soon. I have learned a few things and can pass that along as well. I am located on the Southwest coast of Florida. I will part with it for the price of the paint $125.00

Hello all,

I'm getting a new Mercedes GLB as my company car, to use for the next 3 years.

The car has no extras (basic version), and has the basic 110w sound system (6 speakers total - 1 tweeter and 1 woofer on each front door, and 1 woofer/full-range on the back doors).

I want to upgrade the sound quality (with a limited budget (~750USD) since the car is not mine), and three options were presented to me, by the several car audio shops I talked to:

A) Install a DSP amplifier (e.g. MATCH PP-62DSP or M5DSP MK2) and maintain the stock speakers

B) Install a "regular" amplifier (e.g. ESX QM400.4), and change only the front speakers (e.g. Morel Maximum), keeping the back speakers stock - I could also add a simple subwoofer for about ~100USD extra on my budget

C) Change all 6 speakers for a "good" set (e.g. Focal Performance) and maintain the stock amplifier - cheaper option

From what I read, the trend now is people to install DSP amplifiers.
However I feel I would get a better sound quality with option B than from option A.

Since I'm no expert, what should I go with the stock speakers and only a "new tech" DSP amplifier (option A), or put an "old tech" amplifier and new front and subwoofer speakers?

One of the shops gave me an alert about doing this hybrid solution (B), saying that the Mercedes car system would block the sound or event play it very low on the front/amplified speakers (since it would detect this power change has a "short circuit").

What do you think?
Should I go "new tech" or "old tech"? Option C? Or even a D one no one told me about?

PS: I am from Europe, I usually listen to vocals and accoustic/unplugged music (via CarPlay or USB flacs), and I usually drive alone.

Hi,

I am wondering if anyone of you know where to source quality
USB 2.0 type A and B connectors in the USA?

Gold plated is preferred and with shell casing (most of them I see are only the bare metal connectors.

FYI, I want to DIY my own USB cables.

Thanks so much!

Does anyone know if there's a replacement for the neon bulb NL1? The original is hard to come by and I don't want to replace it with LED (would be last resort). Perhaps I can use NE-2 with resistor, but I don't know the specs of the NL1.

I recently acquired a Denon DCD-960. There are plenty of threads that touch the DCD series, but none that I've seen that includes the 960, or the x6x series. I'm handy with basic electronics and soldering, but most of the DAC-related stuff in CD players is over my head.

What's the best way to improve the analog output section of the 960? I plan to do some recapping, but I'd like to know what circuits to cancel, and whether replace DCD-960 with better DACs and op-amps.

I attach a couple of images with schematics and a list of ICs in case it's helpful.

Circuit Board

ICs and transformers

I have an old Bryston 3B pro with blown fuse on the right channel 🙁 .What I did:
1/ Replaced 5A fast acting, plug in with light bulb limiter, bulb lit up bright.
2/ Removed right channel module, plug in, bulb dim.

I intend to check the BR6522/ BR6521 and SJE1490/ SJE1491 but I am not really sure how to remove them for checking.
My questions: (I am a beginner, bare with me please.)

1/ Is there any way to check them without remove from circuit (I think less likely)

2/ If not then these steps I would want to take:

- Desoldering all 6 transistors.
- Remove 8 screws which attached transistors to heat sink
- Remove 8 screws which attached metal case to heat sink.
Let me know if these are the right way or any thing I am better watch out as beginner may miss.



Thanks,
Troy

Hello everyone,

Nothing is visually damaged on this board, I have measured the DC coming from the PSU and compared it to the right channel and it’s correct, even the LEDs light up, I have also noticed that they stay lit much longer than the ones on the right side after turning the Amp off.

I’m not a Pro, I got 2 of these amps because of what they represent and I was hoping I could fix them but with the very little information I could find about them it looks like I chose the wrong Amp to learn 🙂

Any suggestions from those that have seen something similar?

Any common issues that I should be tackling first?

Thanks in Advance!!

Hi! I’m looking for some advice if BMS 15n630 can be used in closed box of approx 80 liters for subwoofer duty? The high Fs of 39 concerns me, so a «standard» Q of 0.7 in the 80 l box simulate a f3 of about 75Hz... A BR box of 90 l will help the response down to approx 45 Hz. I would like some more extension, preferrably closer to 30 Hz. I know the room will help. And EQ could also compensate, but I can only adjust the crossover frequency (Parasound Hint + bridged Behringer for the sub).

Any thoughts or advice is appreciated!

I am almost positive I had a short on the tone board (my fault...), power amp section seems to work fine if I press 'tone direct' but no sound through preamp.
I pulled all the transistors on the tone board and tested them using the diode function on a MM. Initially I thought the 2SK170s were bad but I may have been testing them wrong. Regardless, bought 4 new LSK170s from Linear Systems. Also replaced the 2SC1845s with KSC1845s since I had them lying around. All the other transistors tested good, which concerns me as I expected to find something toasted.

Paranoid about frying the LSK170s as they are expensive. I have a DBT and a cheap variac I just bought, anything I should watch out for when I power it up? I also have the preamp section disconnected from the power amp for now.



Was planning to just use the DBT and give it a go but thought I would do quick post to see if there was anything else I should be thinking about.

Hello,
So i am struggling to get to grips with sealed speaker enclosure volume math.
I have read and read and some is starting to make sense, plus this little tool is proving a great help.
Speaker Box Enclosure Designer / Calculator

But what to do when Vas is less than Qts as in:
Vas = 0.9l
Qts = 1.04
FRS 8 - 8 Ohm | Visaton

or
Vas = 0.3l
Qts = 1.28
FRS 7 - 8 Ohm | Visaton

or did i miss something (probably)?

Many thanks in advance imk

For my next project, I decided that I want to eliminate the need for a closely matched input pair by using a FET input op-amp instead. I figure it will be an interesting thing to experiment with.

It's far from a new idea- the amp that my design is based off of is the Crest 1001A- which dates back to the 1980s. The schematics for the Crest are attached for reference. Adding a triple EF output stage seems to drastically reduce distortion (at least in simulation).

The design attached simulates quite well, with a few issues that need to be addressed going forward. First is stability- 36 degrees of phase margin seems a little borderline to me. From what I can see, the phase shift is occurring before the output stage.

The 10K square wave simulation looks good, and shows a slew rate of about 85 V/us, which is plenty.

I still need to work out the details of VI limiting on this design, but its implementation shouldn't be much different from any other amp.

I'd love to hear suggestions regarding improvements to this design, particularly from those who have played with this topology before. I'd certainly like to get a bit more of a phase margin if I can, and I'm certainly not opposed to improving distortion.

I have a question related to ringing of output transformers. I have observed this behavior in two different transformers from Lundahl in two different designs, the LL1620 3.3K 60mA and LL9202 6.5K 50mA.

In both cases, the ringing was isolated to the output stage, no visible ringing on the previous stages. Mains transformer ringing is snubbed in both cases.

Here is a 1kHz and 10kHz square on the LL1620 primary.





And 1kHz and 10kHz square on the LL9202 from the primary.





Is it worth pursuing a Zobel network or similar to further damp the ringing? On the LL1620, looks to be near the audio band on the 10kHz square.

The last couple of days I was reading a book about power amp designs and one of the designs mentioned was the hill DX700.
It had to do with sliding bias and a special kind of drive to the output using a transformer.
The driver driving the transformer was just a chip amp (TDA2030).
Looking at the distortion specifications it doesn't look really bad.


Has anyone used these? and comment on the sound?
I do like to check out some of these more obscure designs.

What would a modern version look like?
A few things for modernizing could be a more modern chip amp (lm3886?), using a class H output but still using the sliding bias arrangement if possible.
Use a Sziklai output stage instead of just driving the outputs directly.
Less loading of the chip amplifier so less distortion I think.

I'm just thinking out loud now but the design looks like it worked good so why isn't it used anymore? I am still in the process of figuring out how exactly the sliding bias works

For sale completed with original parts from Salas,used but in good working condition regulator.I will give to the buyer reserve irf840,sk117gr and dn2540 transistors.Price is 40 euro plus shipping inside EU.For offer or other question contact me.

I have just built some foamcore Karlsonator speakers (0.53x) using W5-2143 drivers - they exceed expectations - and would like to add a pair of subs to these, using a Karlson design as well. Not in foamcore, of course.

I'm just wondering whether the drivers I have - Dayton RS270P-4A (Reference paper 4ohm units) might work in such an enclosure?

Has anyone any experience with either these drivers or similar in an appropriately sized Karlson enclosure?

The mains get to about 50Hz in room so if I can get the subs down to about 25Hz that would be more than adequate.

Failing that, I have RSS265HO-44 and RSS390HO as single sub alternatives.

Specs:
Nominal Diameter10"
Power Handling (RMS)100 Watts
Power Handling (max)200 Watts
Impedance 4 ohms
Frequency Response 23 to 6,000 Hz
Sensitivity 90.9 dB 2.83V/1m
Voice Coil Diameter 2"

Thiele-Small Parameters
Resonant Frequency (Fs)22.9 Hz
DC Resistance (Re)3.9 ohms
Voice Coil Inductance (Le)0.55 mH
Mechanical Q (Qms)1.35
Electromagnetic Q (Qes)0.34
Total Q (Qts)0.27
Compliance Equivalent Volume (Vas)3.9 ft.³
Mechanical Compliance of Suspension (Cms)0.66 mm/N
BL Product (BL)10.9 Tm
Diaphragm Mass Inc. Airload (Mms)73.2g
Maximum Linear Excursion (Xmax)6 mm
Surface Area of Cone (Sd)346.4 cm²

Anyone recognize the FR drive unit in the eMOTION?

I asked the manufacturer and was ignored.

[/url]

Hi guys,

I am working on an idea of having a fully DC coupled design input driver stage / phase splitter.

The idea is to use a 6AU6 in triode (I like that tube), DC coupled to the first section of 6SN7, that one DC coupled to the second section of that 6SN7 used as a classic phase splitter. I know cascading sections in DC coupled mode can be challenging, but that's all part of the fun.

On simulation, this works, quite well.

Any glaring mistake you guys see in this design?

I know the current in very low in all 3 tube sections an this could create problem, especially with the LED fixed bias component. If this become a problem, I can always come back to a classic cathode bias resistor.

Also I want to keep the splitter design.

Thank you
Brice.

This morning, I powered on my UPL analyzer only to be greeted with no hard drive detected and CMOS battery failure.

I have the recollection that when I serviced this unit last year, I changed the lithium battery on the computer board. But I'm not 100%, so I pulled the UPL out of service, pulled the cabinet off, removed the speaker and unbolted the motherboard. Took the old battery out, tested it. It shows 3.1 volts. Hmm. I MUST have put this battery in last year.

Needless to say, since I had it apart, I put in a new battery (after checking that it read over 3.1 volts) and put it all back together.

Booted it, and put in all the disk parameters and launched the analyzer software. To check things, I shut off the UPL, waited 15 seconds, then powered it back on, only find out that it lost the CMOS setup for the hard drive and was complaining still about a CMOS battery failure.

This is the only battery I can find on the entire analyzer. What in tarnation is going on here??

I recently got hold of a pair of these monster mono block amplifiers and documented the story on Audiokarma...

I got them from a scrap dealer and as expected they didn't work. The problem appears to be that the same pcb in both amplifiers has been messed around with by someone in the past. One has had parts removed, the other has had incorrect bits added.

The problem is no schematics or circuit diagrams exit for these amps, and every tech I have contacted has said they can't help.
I have tried to contact anyone related to NRG control to no avail.

At 55kg , with 48 output transistors and a transformer larger than a brick each , I REALLY want to get them working, even if it isn't practical to use 400w class A amps everyday, one day I might just have a use for them.

The original plan of hoping a tech could figure out the problem without a diagram didn't work.

Next I thought about reverse engineering the pcb and drawing a circuit diagram from that, but it would take ages AND only give me the diagram for that particular board, there are 2 other similar sized boards + all the outputs + the power supply section which would take far too much time to draw out...

The latest idea was to build a clone of a more popular amp, like a Krell KSA 250 based around the power supply and chassis of the NRG amps....

Can anyone advise...?

Hi folks!

I am facing a dilemma. I have bought M6 grade EI-120 lamination mostly for winding power transfomers and chokes. Now I have to choose bobbins, but unfortunately seller packing only one size per shipment.

I added a size for all available bobbins, of course for power transformers the bigger bobbin the better, but for chokes the bigger size probably will be overkill.

What size do you think will be optimal for EI-120 lamination?

Hello. Model CD275 with VSS: designed with a Voltage Selector Switch for int'l use. Thanks to fellow member 'joydivision' for assistance to get started. I want to eliminate the VSS and hardwire to the PT. The 1st attachment are his instructions for rewiring primary leads.The Marantz schematic found in HiFi engine doesn't show wire insul. colors & I need help. Thank You. Today: 03 Sep, with a magnifying glass I was able to see molded numbers on the interior of the green switch plate of the volt. adaptor corresponding to schematic numbers. One step closer. I apologize for the non viewable pictorial attachments. I will try again.

Very briefly:
I would like to buy and send me a tangential turntable which I've found at the local ebay site in Germany.
The selle won't ship: only will deliver on hand in the nearby of Köln or pickup. I've tried hard to convince him but with no succes🙁
If there is anybody at the diyaudio forum from Köln that can give me a hand, I really appreciate your help.
Just drop me a PM and I'll come back with more details.
Thanks (danke) very much in advance for yor time and interest.
John

Hi all !
A dynamic signal analyzer that has been idle for many years, I have not conducted a power-on test at this time, and I am not sure whether it is operating as expected. The current state I am planning to handle at a low price, $1000.00
The project location is in China.
Of course, if the buyer has a request, I can ask the engineer to do a detailed test. But it will increase the cost of testing.
Let's take a look at the internal state first:

I want to switch between output transformer taps and also between output jacks. It’s for a tube based headphone amp/preamp. Since I won’t be the only person to use this device, I would like to make the switching as idiot proof as possible. I’m envisioning someone playing with the switches at full gain and trying to imagine what might go wrong. The goal is to avoid shorting across the secondary winding or leaving the secondary unloaded. What do you all think of the attached schematic? Overkill or not? Is there a better way?

Thanks,
Marty

Someone emailed me about a box design they saw online.

So I thought I'd put in some time to show what I think it's doing.

In a nutshell, you can combine vented and bandpass enclosures and achieve some interesting results.



Here's a sim that shows the combination of a bandpass box and a vented box. The woofers are the same, an Alpine SWS-10D2.

In the frequency response, you can see that the response curve of the two boxes are comparable. If their phase is identical they'll sum constructively.

Because one is vented and one is bandpass, you might think that the phase response would vary. But with some juggling of the parameters, you can get it fairly close. These two boxes have a group delay curve that's basically the same, down to 35Hz, so they WILL combine constructively.

Below 35Hz, the phase of the two boxes varies quite a bit. This is because the vented box sees 180 degrees of phase shift at it's tuning frequency. At 35Hz, the two boxes are 135 degrees out of phase.

This situation can be addressed fairly easily. For instance, you might use a steep high pass on the bandpass box, so that it's output is reduced below 35Hz. The bandpass box is already radiating 3dB less output than the vented box at 35Hz, so attenuating it another 6dB probably wouldn't be a big deal.

Another option might be to manipulate the phase using FIR filters, all-pass filters, or just plain ol' active filters.

To me, the most interesting aspect of the design, by far, is that the impedance of ONE subwoofer is very high when the OTHER one is LOW, and vice versa. This really has the potential to increase your maximum output, if the two subs share the same amplifier. For instance, at 51Hz the bandpass box is receiving 500% more power than the vented box. At 30Hz, the vented box is receiving over 200% more power than the bandpass box.

So this becomes a "yin yang" thing, for the amplifier, where one sub is drawing a ton of power at a frequency, while the other is not.

In my old home theater, I had a tapped horn, a vented box, and a bandpass box, all at the same time. That worked really nicely, and operates on the same principle.

This thread was inspired by a discussion here:

https://www.diyaudio.com/forums/subwoofers/359383-active-compliance-management.html

This amp uses STP80NE06 as the power supply fets since they are obsolete do you know of a good replacement ?

Also do you happen to know the part number for the part next to it circled is it some type of switch ? The board location is SW3

With SG 3525 and wanna share the Gerber files?

Hello

Recently I could pick up two vintage Goodmans Woofers as well as other components from an old estate.

Id like to build a new enclosure, as the speakers were mounted in the furniture and did not come with a cabinet.

Tested the woofer in free air and some 140 L sealed enclosure that was lying around, to check them. The go up to 4-5 kHz, are very! sensitive but are difficult the get any deep bass from.

They seem to be very special model with very high BL and very low Qes. Id like to hear about any experience with high BL / low Qes Drivers anyone had.

Some info on the woofer

Goodmans Audiom 852

Size 12 inch, 313mm overall diameter
Weight 26 lbs, 11.8 kg (heaviest 12'' speaker I ever laid hands on)
Total flux 308000 Maxwells (highest number I've ever seen)
Fs 35 Hz
Re 15.8 Ohm and 15.6 Ohm (Highest I ever measured)
3'' voice coil

By comparing with other modells, 308000 Maxwells would correspond with 16'000 Gauss flux density. Taking in account the Re and comparing with other Goodmans woofers I would estimate a BL of around 32.

Does anyone have experience with such woofers?

Thanks a lot for any info.

Martin

I came across a Mitsubishi M5218AL (SIP 8 pin) amongst my junkpile of stuff.
It's a very low distortion dual op amp mainly used as a headphone amp in some equipment.


I'm curious, and open to suggestions before I go into anything with this, but would it be possible to use this chip as a pre-driver of sorts to drive some hefty output transistors directly, or with an additional transistor before the outputs?

Hi all,

Today I finished a subwoofer for my car using the Scanspeak 30W/4558T and 30W/0-00 in a 70.8 litre (2.5 cubic foot) enclosure. The box uses 19mm MDF and is heavily braced, I made allowance in the box volume for the bracing, sub and passive radiator displacement and I covered the walls in 25mm convoluted foam. The amplifier is a 600 watt Class D that is very clean and well behaved, I have the input sensitivity turned well down.

The result is less than good, the bass is tubby, one noty and the the sub seems to overload at even low volume. I haven't measured it yet but I can not live with it as is. Would anyone care to hazard a guess as to what I might have done wrong or what is going on here?

Thanks.

Hello all,

New project, just took ownership of a couple of Quad 2 monoblocks and the Quad 22 preamp.

Will be restoring the Quad 2s to 'like new' and well in hand on that..but.

For the Quad 22 pre-amp, no benefit in restoring that value tech, so want to install a MQA capable DAC into it and a more current value pre-amp.

Looking for suggestions on DAC PCBs, and tube kits/design with tone and filter controls, so I can keep the Quad 2 exterior as standard.

Thanks in advance.

Malcolm

Hello, I came across this schematic.

https://www.electroschematics.com/mosfet-audio-amplifier-irf9530-irf530/

To my understanding, the opamp is loaded with the 240ohm resistor, and the signal is taken from the current consumption of the opamp ? Is my understanding correct ? Is that really smart or really ugly ?

Thank you 🙂

Hi all, after much lurking and reading got inspired to take on my first tube project.

Looking for some guidance with a vintage single ended el84 amplifier. This was pulled from a Motorola record player, the objective is to convert it to a stand alone stereo amp.

I've done the following so far: replaced power cord with grounded 3 prong (no death cap in the circuit that I could see), added on/off switch and fuse holder. Have also replaced all power filter and coupling caps.

I am not intending to use the old volume, tone or balance controls. The amp uses 2 12ax7s in the pre-amp stage, one half of each tube appears to be for gain ("1st AF Amp) and the other is labelled "Tone Amp". Both driver tubes have connections back and forth to the tone control panel.

And this leads me to my question, upon reviewing the wiring and schematic I'm not sure where to wire my inputs for stand alone use? Do I need to use both driver tubes to get adequate gain or can I bypass the 'tone amp' triode section on each channel (if not using the tone controls)? I'm pretty sure there may be some re-wiring involved but looking for the simplest way to get this running.

Attaching the schematic, any help much appreciated.

Hi does anybody Know what this is? is it an IC in A to-3 package and anybody has datasheet for this? also This TA78005M that I think is a regulator.

Found them in a bulk sale of old trannies with some kinda old and unfamiliar semiconductors.

I recently finished my second speaker build, but the listening experience and tests with an OmniMic system reveal an unexpected lack of low-end. Given that the drivers are only 3 1/2", I wasn't expecting a lot of bass, but the it had substantially worse frequency response than the driver manufacturer's specs. How did I go wrong?

Design details:

• Two Dayton Audio PS95-8 full range drivers.
• One port that is ~6" long and 2.5" in diameter with a flared end.
• Box has ~650 cubic inches of interior volume after taking drivers and components into account. I calculated the ideal volume as 775 cubic inches, and I may try stuffing the box with some kind of acoustic treatment to "inflate" the perceived volume.
  
• Uses a Dayton Audio DTA-2 Class D Digital Audio Amplifier Module.

Attached images:

• Two frequency response results I got from measuring the finished product with OmniMic. One is at a higher SPL level.
• The frequency response of the driver, supplied by Dayton.
• The low-end response of the box, as calculated by Speaker Box Lite.
• The finished box to give a sense of the design.
  

My analysis:

The driver frequency response from the manufacturer is flat until about 100Hz. The calculations I did with Speaker Box Lite estimated a port tuned to about 66Hz would keep the response flat down to about 50Hz.

To my dismay, the finished product seems to start dropping off at ~1kHz. When listening to music, the low end is pretty absent. Kick drums lack body and baselines are hard to pick out. Any help understanding what is going on here would be greatly appreciated!

Started the 2way design with SB Acoustics SB13PFC25-4 Paper Cone Woofer and SB26ST-C000-5 Soft Fabric Dome Tweeters

Specs:
2way Floorstanding Speaker from 5'' mid-bass and 26mm dome tweeter.
Cabinet Volume: 8Ltrs
Woofers: SB13PFC25-4
Tweeter: SB26ST-C000-5
Nominal Impedance: 4 ohms
Port tuning Frequency: 45Hz
Cabinet Material: 6mm MDF + 12mm Pinewood
Cabinet External Dimensions: Height - 870mm X Width - 175mm X Depth - 232mm

Xover Design, Cabinet CNC Data, and Measurements will share soon

I'm taking apart an Onkyo amp from 2015. I'm breaking it into two projects. I'm building a 500W sub and a DAC with Amp for my HiFiman HE-5Se headphones. The amp has all the chips PCM, ARM processor, 128MB RAM etc. but no Bluetooth IC. I'm looking for a digital Bluetooth receiver IC, no built in DAC and pre-amp. Suggestions? I want my music to play from my phone and need to transmit and receive a PCM signal. Feedback welcome . . .

For anyone who has been frustrated trying to figure out how best to physically lay out and wire a tube amp, these boards might be of assistance. The come in 9 pin, noval, or octal configurations for twin triodes. I purchased the 9 pin version (octals out of stock) to play with. The quality seems good, and they're very flexible as to the configuration. The schematic and information is downloadable.
And the standard disclaimer - I don't work for, or know, these people and have no vested interest in anyone purchasing them. Just thought I'd share the info.
DIY - www.thetubestore.com
PS - if this should be in 'Parts', I apologize, and assume someone will move it.

HI,

I friend have an old Symetrix 544 comp. But the power transformer is burned. So, I need a replacement, the problem is that I have no idea what type of transformer is. The manual have some schematics, but is unreadable. The only that can help, maybe are the voltage regulators.

78M12
79M12

78M15
79M15

Anybody can help?

Thanks.


https://i.ibb.co/mBz2fcL/IMG-20200821-193448494.jpg

Hi guys,

(I have tried the search but i couldn't find my answer, hopefully i used the right search).

I'm trying to find a panel mount connector for my phono preamp projects which should have 3 conductors for feeding power from my dual voltage power supply (positive/negative DC outputs plus ground) to the preamp .

I've been trying to locate something for a month now, and the only type of 3 pin connectors i found was XLR female (or male) panel mount connectors which i'm not sure if it's the right thing to use.

Have you any suggestion where should I look for such DC connectors ? I'm struggling with my limited electronic components knowledge...

Amplifier is drawing excessive current at idle. 3amps.
I rebuilt a power supply, the original gate resistor were 20R I changed them all to 47R and irf3205.

No shorted outputs, no shorted power supply mosfets.

Runs a tl494c.

I'm looking at the Mini Dissipante 3U (250mm) and the Slimline 2U (280mm alum) for two different projects and I'm trying to find information about the size of the internal brackets. From the photos I've seen, these look like they are about 10mm x 10mm angle brackets along the top and bottom and up a little on the back and front panels. Is there a drawing available anywhere that shows the exact dimensions?

Thanks.

At last I have a successfull experiment 😀

I like transconductance amplifiers (high output impedance) and I like the Aleph J, and so of course I wanted to combine the two!

My thought process was:

1. Start with a normal Aleph J
2. Convert it to use a single sided supply because that is what I have: I added R51-R55 to a normal Aleph J and omitted R2.
3. Reduce voltage feedback by X: In the end upping R4 by 4x to 820k reduced this by ~ 12 dB.
4. Wrap a current feedback loop around it for ~ 12 db of current feedback and connect it to the negative input. Here I reduced R3 to let me use a smaller current feedback resistor in series with the speaker to waste less output power.
5. Get the result of an Aleph J with same distortion spectrum but with high output impedance, a current source amplifier like the F1 and the F2 without impedance reducing resistors.

And in the end it worked perfectly. I get the same distortion spectrum as a normal Aleph J, same-ish output power and most importantly ~ 120 ohm output impedance instead of the 0.4 ohms of the real Aleph J.

And an additional note: With a single sided supply we need the voltage feedback loop. Without it the current feedback makes the amp oscillate. Amplifier topologies for current-drive | Current-Drive - The Natural Way of Loudspeaker Operation explains this.

Hi,

I wish I could add an application for room equalization for the open source
project Aida DSP.
I've started reading here
https://www.minidsp.com/applications/digital-room-correction/drc-basics
and then here
Transfer function modeling and equalization by fixed-pole parallel filters

It seems that the measurement of the room response has to be done by Pc with audio card + Mic. Then you generate the desired compensation curve and
try to approximate it with a cascade of IIR filters, which run on DSP hardware.

I can do an application for Arduino that load DSP coefficients after a room measurement, but I need really someone who just tried some
of the existing algorithms.
The final application will be opensource and will run on Aida DSP board which is ADAU1701 based.

Thank you! 🙂

So, I have maxed out on building LM3886 chip amps and want to level up to Papa Nelson Pass Class A's.

What is the recommendation and ethical way forward for PCB sourcing ?

In particular, I plan to build an F5 as it seems to be loved by all, and is probably just what I want, a classic 25w class A.

The challenge is getting a PCB...

The diyaudio store has been out of stock for ages, ebay is full of "inspired by" PCB's that seem to claim some relationship to the original Pass design.

So what to do?

Are the diyaudio boards likely to return to stock, are they authentiic to the Pass design.

If the philosophy is "open source" are the gerber files published?

I acquired parts for this amp but have way too many projects so selling at nice discount.

SOLD Baby Huey EL-34 Kit - PCB's (2* amp, 1* psu from latest GB), 95% BOM (PDF attached with part list), Toroidy TSTA250/001 and ceramic tube sockets

SOLD Hammond 1650PA 60W 6.6K OPT

SOLD Hammond 159V Choke

SOLD Gold Lion Genalex KT-77 - $120/quad (platinum matched from Upscale Audio, used less than 20hrs)

SOLD Telefunken ECC83/12AX7 smooth plates (Fisher logos), test at 45/45, 45/47 which is 90-95% of new. $90/pr

Looking for the schematic for a US Amps MD-2D. I cant figure out what goes in Q2C in the picture I've attached